SE466690B

SE466690B - PROCEDURE FOR EXPLOSION WELDING OF Pipes

Info

Publication number: SE466690B
Application number: SE8803131A
Authority: SE
Inventors: P I Persson
Original assignee: Exploweld Ab
Priority date: 1988-09-06
Filing date: 1988-09-06
Publication date: 1992-03-23
Also published as: SE8803131L; SE8803131D0; GB2222381A; GB8919899D0; GB2222381B; US4981250A

Description

466 590 Fig. 1 visar skarvens konstruktion. Siffrorna 1 och 2 betecknar de bada rörändar, som skall sammansvetsas. Den ena röränden 1 har avfasats pà insidan med en vinkel av maximalt 15”. Den andra röränden 2 har utpressats till en kon med vinkeln 5”. á En explosionssvetsningsladdning 3, utgöres av en gjuten laddning bestående av sprängämne, t.ex. PETN, HMX eller RDX, bundet i en matris av silikongummi. 466 590 Fig. 1 shows the construction of the joint. The numbers 1 and 2 denote the two pipe ends, which are to be welded together. One pipe end 1 has been chamfered on inside with an angle of maximum 15 ”. The other pipe end 2 has been extruded to a cone with the angle 5 ”. á An explosion welding charge 3, consists of a cast charge consisting of of explosives, e.g. PETN, HMX or RDX, bonded in a silicone rubber matrix.

Förutom sprängämnet ingår tillsatser av järnpulver och glassfärer i ladd- ningen.In addition to the explosive, additives of iron powder and glass spheres are included in the ningen.

Laddningens recept är anpassat så att en detonationshastighet av 3700 m/s till 4300 m/s, företrädesvis 3900 m/s, erhàlles.The charge recipe is adapted so that a detonation speed of 3700 m / s to 4300 m / s, preferably 3900 m / s, is obtained.

Siffran 4 betecknar en kapsel av plastmaterial med den form figuren anger, kapseln 4 säkerställer laddningens placering i förhållande till rorändarna 1,2 samt laddningens 3 exakta dimensioner.The number 4 denotes a capsule of plastic material with the shape indicated in the figure, Capsule 4 ensures the location of the charge in relation to the rudder ends 1.2 and the 3 exact dimensions of the charge.

En tändladdningsskiva 5 utgöres av ett högbrisant sprängämne, t.ex. PETN, RDX eller HMX, bundet med silikonolja, plast eller latex, dock sä att sprängämnet utgör minst 70% av laddningens vikt.An ignition charge disc 5 consists of a high-explosive explosive, e.g. PETN, RDX or HMX, bonded with silicone oil, plastic or latex, however the explosive constitutes at least 70% of the weight of the charge.

Skivan 5 är utförd pà detta sätt för att ge tillräckligt detonationstryck för en fullgod initiering av explosionssvetsningsladdningen och medge detonation i tunna skikt för att totala laddningsmängden skall kunna minimeras.The disc 5 is designed in this way to give sufficient detonation pressure for a proper initiation of the explosion welding charge and allow detonation in thin layers in order for the total amount of charge to be able to minimized.

Plastkapseln 4 och därmed laddningen 3 har en axiell utsträckning sá att detonationens stabila tillstànd hinner uppnås innan detonationsfronten när rörändens 1 spets.The plastic capsule 4 and thus the charge 3 has an axial extent so that the stable state of the detonation has time to be reached before the detonation front reaches pipe end 1 tip.

Härvid är avståndet från tändskivan till den fasade rörändens spets minst omkring 5 mm, företrädesvis minst omkring 6 mm.In this case, the distance from the ignition plate to the tip of the bevelled pipe end is the least about 5 mm, preferably at least about 6 mm.

Resultatet av detta är, att en fullständing bindning erhålles i spetsen, vilket förebygger möjligheterna till spaltkorrosion. 3 g 466 690 I fig. 1 anger 7 en brottanvisning i form av ett slipat spàr. Dä den reflekterade stötvágen frán röränden 2 när denna avskjuvas material runt om längs brottanvisningen. Den avskjuvade delen tjänar därför som vâgfälla och fullständig bindning erhàlles pà den kvarvarande delen av röret. vid utprovning av vinkeln mellan konens insida och den raka röränden har 5° visat sig ge mycket goda och reproducerbara svetsar vid ferritiska rostfria rör av Duplextyp.The result of this is that a complete bond is obtained in the tip, which prevents the possibility of crevice corrosion. 3 g 466 690 In Fig. 1, 7 indicates a fracture indication in the form of a ground groove. Then it the shock wave from the pipe end 2 reflected when this material was sheared around about along the crime scene. The sheared part therefore serves as a cradle and complete bonding is obtained on the remaining part of the tube. at testing of the angle between the inside of the cone and the straight pipe end has shown 5 ° give very good and reproducible welds to ferritic stainless steel pipes of Duplex type.

Vid mera lättsvetsade material är det möjligt att använda vinklar ned till 3°, utan att reproducerbarheten äventyras. Fasvinkeln 15' har visat sig ge bra bindningsresultat i spetsen. Mindre vinklar än 15' är också fullt godtagbara, men ger onödigt stor laddningslängd, utan att nämnvärt förbättra resultatet.For more easily welded materials, it is possible to use angles down to 3 °, without compromising reproducibility. The phase angle 15 'has been shown to give good binding result in the tip. Angles smaller than 15 'are also full acceptable, but provides unnecessarily large charging length, without significantly improving the result.

Större vinklar än 15' ger sämre reproducerbarhet i spetsens bindning.Angles larger than 15 'give poorer reproducibility in the binding of the tip.

Claims

466,690 Patent claims

1. A method of welding pipes to pipelines by means of explosion welding, characterized in that one pipe end (2) is formed into a cone with the angle 6 '- 20', preferably 10 'and the other pipe end (1) is chamfered on its inside by a phase angle of 12 '- 17 °, preferably 15', in that the charge (3) comprises an explosive which, together with iron powder and hollow glass spheres, is molded into a matrix of silicone rubber to such a composition that a detonation speed of 3700 m / s - 4300 m / s, preferably 3900 mls are obtained and by said charge (3) being initiated by a thin charge disk (5) with a detonation speed of at least about 6500 m / s, which charge (3) is contained in a plastic capsule (4), whose shape is adapted to the internal configuration of the pipe ends and the outer diameter of the charge so that the position of the charge (3) contained in the plastic capsule (4) in the axial and radial direction relative to the pipe ends (1,2) is determined, and that the distance from the ignition plate (5) to the bevelled pipe end even (1) tip is at least 5 mm, whereby the detonation in the explosive in question has reached a constant speed before the welding process begins.

2. Set acc. claim 1, characterized in that a fracture indication in the form of a circumferential groove (7) is made at least 10 mm from the end of the conical part.

3. Set acc. claim 1 or 2, characterized in that the charge (3) is based on the explosives PETN, HMX or RDX, which with admixture of iron powder or corresponding and hollow glass spheres are given said detonation rate.

4. Set acc. claim 1, 2 or 3, characterized in that the tooth charge plate is initiated in its center so that a completely axially extending detonation is obtained in the explosion welding charge.